$ sudo apt-get update
$ sudo apt-get install fcitx-sunpinyin 

fcitx-sunpinyin is installed in your system.

Make ensure the fcitx-sunpinyin package were installed using the commands given below,

$ sudo dpkg-query -l | grep fcitx-sunpinyin *

You will get with fcitx-sunpinyin package name, version, architecture and description in a table

fcitx-sunpinyin package basic information: